"Photography is one percent inspiration and ninety-nine percent moving furniture." Arnold Newman“Don't bother just to be better than your contemporaries or predecessors. Try to be better than yourself.” William Faulkner

Are you talking about jelling the lights themselves? There are dozens of different color light, warm white, cool white, super savers, full spectrum etc. They all require different gels. Frankly I have a case full of them but haven't used them in years-since I shot film.

"Photography is one percent inspiration and ninety-nine percent moving furniture." Arnold Newman“Don't bother just to be better than your contemporaries or predecessors. Try to be better than yourself.” William Faulkner

I thought you were talking about room lights. And what are your lights? So you want to gel your lights to match in-room fluorescents? Again there are dozens of different kinds of fluorescents. Do you have access to a color temp meter. Frankly I have solved this by doing separate exposures for each different light source and blending as layers in PS.

I dunno about two different gels just for fluorescents. Like Kirk says, they're all over the place in terms of color, but some amount of plus green should handle it pretty well. Keep in mind that the old-fashioned tubes oscillate at 60mhz, which means that if your shutter speed is faster than 1/60th, you'll capture a different section of the cycle every time, with a slightly different color temp. It'll make you crazy.I haven't noticed this with CFLs. But I'm rarely above 1/60th...

One really useful combination (for me) is plus green with 1/2 CTO. This is GREAT with mixed Halogen and fluorescent lighting.

I used to use one of the 3 Lee FL-D filers on the lens and then add an 82 series filter to take out some of the warmth from halogen spots that often featured in the shop interiors I used to shoot. This was back in the days of film, so would Polaroid each fl-d to see which one matched the tubes then add some blue with the 82. With experience I was getting the colour very close considering the mixed lighting.

"Photography is one percent inspiration and ninety-nine percent moving furniture." Arnold Newman“Don't bother just to be better than your contemporaries or predecessors. Try to be better than yourself.” William Faulkner

Rosco used to sell something called the Jungle Safari kit. It had CTO, CTB, plus-green, and plus-magenta gels in full, half, quarter, and eighth values. Combining different gels could balance flash to pretty much any ambient. I see they list a "color correction kit" now that has only blue and orange (CTB and CTO.) Too bad.

For balancing flash to fluorescent, it really depends on which type of bulb is in the room. Lots of rooms on our campus use Warm White Fluorescent, which is about 3600K and has a color correction of ~24 magenta in Lightroom. Balancing a flash requires a Half or Full CTO and about a 1/2 so Plus Green (green filter.) That gets in the ballpark.

Other fluorescents might be 4000-4400K, or even "daylight" at 5000K or so. Almost all of them will require some green over the flash to balance, but different amounts of orange, or none at all. The key is to test, then test again, and keep copious notes.

Also note that different flash units will require slightly different filter packs.

What you have here matches closely with I have been wrestling with. I do a lot of work on college campuses, and I need to blend flash with ambient all in one file in the camera.

For balancing flash to fluorescent, it really depends on which type of bulb is in the room. Lots of rooms on our campus use Warm White Fluorescent, which is about 3600K and has a color correction of ~24 magenta in Lightroom. Balancing a flash requires a Half or Full CTO and about a 1/2 so Plus Green (green filter.) That gets in the ballpark.

Other fluorescents might be 4000-4400K, or even "daylight" at 5000K or so. Almost all of them will require some green over the flash to balance, but different amounts of orange, or none at all. The key is to test, then test again, and keep copious notes. Also note that different flash units will require slightly different filter packs.

Johnathan Wienke in 2005 had a post (below) I found really interesting and helpful. I have used variations on what he outlines here and made my own gels for canon strobes with with some good results with compact florescents.

Yes, there are a million different flavors, and for me it usually mixed light, something interior photographers correct with layered files.

I have never tired mixing green with a cto. It does make sense when I look at corrected white balance adjustments in Lightroom. I'm looking now at a corrected file in Lightroom is showing 2950K and +7 on tint. (Does 7 tint equal 7cc on filters? I probably knew that for sure at some point.) I have found that Cut to Straw (CTS) can be a better match to the ugly yellow/orange that passes for warm in warm florescents.

I have a bunch of 30 green gells from back in film days. I have found them way too much green with digital and light out there now. I'll have to find my old rosco sample pack and try some paler greens.